The invention relates to a monitoring system as well as to a method involving a monitoring system for standard use in the process-accompanying monitoring of tools, workpieces or treatment processes in machine tools of the cutting type.
Those components of machine tools which are subject to wear or which are susceptible to damage due to machine collisions, machine overstressing or imbalanced tools or workpieces, are in need of monitoring. Such machine components are substantially those which carry out movements in the machine tools. Therefore, they are substantially restricted to feed slides, tool and workpiece spindles but also include aggregates for the further operation of a machine tool of the cutting type.
Provided that a monitoring system for the process-accompanying monitoring of tools, workpieces or treatment processes has been installed, the method of the invention makes it possible, in performing the monitoring or checking of feed slides and tool and workpiece spindles, to obviate the need for separate monitoring devices, resulting in a considerable potential for cost reduction because the hardware, the software, the operating means and the interface for machine control need not be provided twice.
There exist several known monitoring devices for the monitoring of vibrations on rotating machines and machine components. These are primarily useful for the detection of vibrations and imbalances in engines and transmissions and partially also for the detection of imbalances in machine tool spindles. Some of these devices are also adapted to detect damage on bearings by means of vibration measurements (e.g. the Vibration Monitor VIMO 100 of PROMETEC GmbH, Aachen, cf. enclosure “Vibration Monitor VIMO 100”, Prometec company, Aachen, and “Modulares Prozess Monitor System PROMOS”, Prometec company, Aachen). The contents of these printed publications are herewith incorporated by reference into the present disclosure.
Further, it is known that machine tools can be provided with vibration detectors arranged on the spindle housings near the bearings to thus detect damage to the bearings, and that the cables of the sensors can be guided to accessible plugs on the front of the machine tool. From time to time, the maintenance personal will use these plugs to analyze the signals for bearing damage by means of analyzing devices. For this purpose, the signals are recorded by analyzing devices and will be analyzed off-line at a later time. An in-process monitoring is not performed here.
Monitoring systems for the process-accompanying monitoring of tools, workpieces or treatment processes in cutting-type machine tools for rotating, drilling or milling serve the purpose of in-process detection of at least one of the conditions of tool breakage, tool breakout, tool wear, contact between tool and workpiece, rattling or machine collision and—particularly in case of tool breakage or machine collision—shall bring the machine drives to a standstill as quickly as possible to preclude consequential damage.
Such in-process monitoring systems are already provided with an electric interface between the monitoring system and the machine control means so as to perform an in-process monitoring of the signal developments of the sensors at monitoring intervals which are predetermined by the machine control means and, in case of a detection of any one of the above mentioned conditions, to bring the machine to a standstill through the same interface. The interfaces between the machine tool control means and the monitoring system have up to now existed substantially in the form of parallel input and output signals for SPC control. Such a parallel interface between the SPC and a tool and process monitoring system can be designed e.g. in accordance with the BAPSI standard which also already allows for the transmission of data words as tool codes or cutting codes from the NC program to the monitoring system. Only recently, manufacturers of control devices increasingly offer field bus interfaces in addition to or instead of these parallel interfaces; the field bus interfaces make it possible to perform a wider exchange of information between the machine control means comprising the stored program control (SPC) or the NC control.